1. Field of the Invention
The present invention pertains to a method of cleaning a wafer, and more particularly, to a method that is performed prior to a deposition process while the wafer is lifted. Consequently, particles adhered to the front side, the back side, and the bevel of the wafer can be effectively removed.
2. Description of the Prior Art
Normally, semiconductor fabrications are implemented by repeatedly performing deposition processes, photolithography processes, and etching processes. In each process, particles unavoidably appear on the wafer. For instance, a great deal of polymers tend to adhere to the surface of the wafer including the front side, the back side, and the bevel. If the polymers are not removed, they may become a particle source after being heated in the successive processes. This would affect the production yield and product reliability. In a deposition process, particularly, if polymers remain on the wafer, the adhesion between the thin film to be deposited and the wafer may be seriously affected. This leads to a film peeling issue, and influences the production yield.
Please refer to FIG. 1. FIG. 1 is a flow chart of a conventional deposition process. As shown in FIG. 1, the conventional deposition process includes:
Step 10: providing a wafer to be deposited;
Step 12: performing a clean process to the wafer; and
Step 14: performing a deposition process to the wafer.
Although the conventional deposition process includes a clean process, the clean process is performed while the wafer is positioned on an E-chuck of a deposition apparatus. Therefore, only the front side of the wafer is cleaned. The back side and the bevel of the wafer remain unclean.
Please refer to FIG. 2. FIG. 2 is a diagram schematically illustrating a clean process performed prior to a conventional deposition process. As shown in FIG. 2, a wafer 20 to be deposited is provided, and loaded into a deposition apparatus 30. The deposition apparatus 30 includes a reaction chamber 32, an E-chuck 34 disposed on the bottom of the reaction chamber 32 for supporting the wafer 20, a cooling system 36 disposed on the bottom of the reaction chamber 32, and a plurality of RF powers 38 disposed on the bottom, the top, and sidewalls of the reaction chamber 32 to provide different voltages through inductive coils 40 so as to generate plasma.
As shown in FIG. 2, the wafer 20 being cleaned is disposed on the E-chuck 34, and thus only the front side 22 of the wafer 20 is cleaned. Meanwhile, the particles adhered to the back side 24 and the bevel 26 of the wafer 20 still exist. In such a condition, the particles remaining on the back side 24 and the bevel 26 may affect the adhesion between the film to be deposited (not shown) and the wafer 20. The poor adhesion would cause a peeling issue due to heat effect in the following processes, and reduce the production yield.